After disable a connection thread (lower ui panel) be able then to clear the thread when has finished its download part. Clear Disable Thread option for the right mouse drop options for this would be useful to manually clear them.
Could be also automatic where a global option (when not paused) with all threads active if one is below certain speed set by user for xx seconds a new thread will be made and old thread cleared when complete. Maybe xx seconds is initially set to 30 as minimum. Also would help when one or more thread doesn't restart after 30 seconds old thread disabled and new thread made until is working at normal connection speed/all threads.